Chymase-positive mast cells play a role in the vascular component of airway remodelling in asthma

Background: There is increasing evidence to support a role for total mast cells (MCTOT) in the vascular component of airway remodeling in asthma. On the contrary, up to now, no study has addressed the role of chymase-positive mast cells (MCTC) in microvasculature changes. Objective:We sought to assess the role of MCTC in the vascular component of airway remodeling in asthma. Methods: We recruited 8 patients with mild-to-moderate asthma and 8 healthy volunteers as a control group. Fiberoptic bronchoscopy with endobronchial biopsy was successfully performed in all subjects. Immunostaining was performed for quantification of vessels, vascular endothelial growth factor (VEGF)–positive cells, MCTOT, and MCTC. Results: Compared with those from healthy subjects, endobronchial biopsy specimens from asthmatic patients showed increased numbers of MCTOT and MCTC and VEGF1 cells (P <.05). In asthmatic patients the number of vessels and the vascular area was also greater than in healthy subjects (P < .05). Additionally, in asthmatic patients the number of MCTC was significantly related to the vascular area (rs 5 0.74, P < .01) and to the number of VEGF1 cells (rs 5 0.78, P < .01). Moreover, a colocalization study revealed that MCTC were a relevant cellular source of VEGF. Finally, a 6-week treatment with inhaled fluticasone propionate was able to reduce MCTC numbers. Conclusion: MCTC can play a role in the vascular component of airway remodeling in asthma, possibly through induction of VEGF. Clinical implications: Specific targeting of MCTC might be a tool for treating vascular remodeling in asthma. (J Allergy Clin Immunol 2007;120:329-33.) Key words: Mast cells, bronchial asthma, vascular remodeling